The invention relates to jogging multiple industrial robot arms simultaneously with an incremental displacement of both a leader robot and follower robots. More particularly, it pertains to a track jog mode, in which a follower tracks the motion of the leader, and to a mirror jog mode, in which a follower mirrors the motion of the leader.
The term “jog” is a generic reference to teach-time, user-interactive robot motion. A user can teach multiple robots a path to be traversed automatically and repeatedly by teaching one robot and later transferring the taught program to other robots. This method can be tedious if during program execution the robots must execute simultaneously. After transferring the program to the other robots, when changes are required or corrections to the original program must be made, it is difficult to alter the program uniformly for each robot because continuous switching between robots is required to make these changes.
U.S. Pat. No. 3,890,552 describes a system for teaching and operating leader and follower robots to produce coordinated translation along three mutually perpendicular axes, one of the follower's translations being equal in magnitude and opposite in direction relative the corresponding translation of the leader. A switching circuit controls actuators, which produce the programmed translations. The control system produces no rotation about the axes and requires initial alignment of at least one axis of the leader and follower, and accurate spacing of the work heads of the leader from the follower so that coordinated movement can occur.
Coordinated jogging is a well known technique for producing coordinated movement of a follower robot with that of a leader robot, the relationship of the follower tool center points (TCP) to that of the leader being fixed while jogging. But coordinated jogging does not produce the same incremental motion of the follower as that of the leader. The leader frame changes when the leader moves, and the follower must maintain its relative position with respect to the leader frame. For example, when the leader rotates, the follower must rotate with respect to the leader frame and this produces longer distance movement of the follower than that of the leader.
Coordinated jogging was primarily designed to use a positioner as the leader. It was not intended for use with a robot arm as the leader or to teach multiple arm programming when the leader is a robot arm. Coordinated jogging requires users to jog each robot arm individually to a desired location and orientation, and then record the position. Furthermore, coordinated jogging does not support mirror jogging; instead, it causes the follower to move in the same direction as the leader's motion.
Multiple arm track jogging overcomes coordinated jog's shortcomings. Multiple arm track jogging produces the same magnitude of incremental motion of the leader and follower, and it supports mirror jogging. It allows a leader and follower to jog in reverse directions so that a leader and follower can cooperatively process and manipulate a symmetric workpiece concurrently.